2026/07/21 by Shiki Ogata, Shunsaku Kitagawa, Kenji Ishida +4
#cond-mat.supr-con #cond-mat.str-el
We performed 75As nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) measurements on a higher-quality single-crystalline CeRh2As2, a heavy-fermion superconductor exhibiting multiple superconducting (SC) phases under magnetic fields along the c axis. This SC multiphase is believed to originate from staggered Rashba spin-orbit coupling associated with locally broken inversion symmetry. In addition to superconductivity, CeRh2As2 exhibits phase I below T0∼0.5 K and an antiferromagnetic (AFM) state below TN∼ 0.25 K in the early-stage samples. In the higher-quality sample, the AFM transition becomes more pronounced, and TN increases to nearly coincide with TSC. The NQR spectra at the As(1) site imply an internal field with an incommensurate distribution, indicating a two-dimensional incommensurate modulation of the magnetic structure superimposed on a Q=0 A-type AFM component. Moreover, a pronounced decrease in the NQR intensity at T0 well-above TN and an abrupt increase in the internal field at TN suggest the emergence of a slowly fluctuating AFM order at T0 which becomes static at TN.